diff --git a/autoload/vimwiki/vars.vim b/autoload/vimwiki/vars.vim
index 1bdda1a..77689f7 100644
--- a/autoload/vimwiki/vars.vim
+++ b/autoload/vimwiki/vars.vim
@@ -359,7 +359,7 @@ function! vimwiki#vars#populate_syntax_vars(syntax)
   "create regexp for bulleted list items
   if !empty(g:vimwiki_syntax_variables[a:syntax].bullet_types)
     let g:vimwiki_syntax_variables[a:syntax].rxListBullet =
-          \ join( map(g:vimwiki_syntax_variables[a:syntax].bullet_types,
+          \ join( map(copy(g:vimwiki_syntax_variables[a:syntax].bullet_types),
           \'vimwiki#u#escape(v:val).'
           \ .'repeat("\\+", g:vimwiki_syntax_variables[a:syntax].recurring_bullets)'
           \ ) , '\|')